Well... judging from porn it is in fact easier to find blacks with bigger dicks.
In science the only study done on the subject was by Dr Kinsey, and he found blacks and whites actually have roughly the same size dicks, only whites dicks get much smaller when soft.
then biologically- its sort of the be expected that blacks have a bigger penis. would fit nicely with their higher sex drive, agression, deeper voice, bigger jaw, earlier puberty. It would fit the pattern.
Asian men are hardly even men. They´re just not-female.